Python 3 functions and lambdas cannot take explicit tuple param

[cclauss]

I will provide a PR for these...

./artemis/ml/datasets/art_gallery.py:48:18: E999 SyntaxError: invalid syntax
def get_new_size((cy, cx), new_size):
                 ^

./artemis/ml/datasets/datasets.py:109:59: E999 SyntaxError: invalid syntax
        return self.process_with(targets_processor=lambda (t, ): (encoder(t), ))
                                                          ^

./artemis/ml/predictors/train_and_test.py:169:27: E999 SyntaxError: invalid syntax
    def __getitem__(self, (data_subset, prediction_function_name, cost_name)):
                          ^

./artemis/plotting/matplotlib_backend.py:260:28: E999 SyntaxError: invalid syntax
def _update_axes_bound(ax, (left, right), (lower, upper), mode = 'fit'):
                           ^